FIELD
[0001] The present invention relates generally to an isolation gasket which is adapted to
be interposed and compressed between joined pieces of pipe in a flow line that is
operative for fluid flow therethrough without leakage. Such gaskets are known from
US 2006/0220324. More particularly, the present invention is directed to an electrical isolation
gasket that is part of a seal system which is particularly useful in high pressure,
high temperature and/or highly corrosive environments. The seal device of the present
disclosure is specifically adapted to provide enhanced fire resistance and electrical
isolation between joined pipe sections.
BACKGROUND
[0002] Seal systems using gasket devices are well known and have been used in a variety
of applications to prevent fluid from leaking between joined pieces. For example,
a seal device is interposed and compressed between flanged end connections of a flow
line. In some cases, in-line process control equipment is to be installed at various
points in a flow line, and may be associated with flanged end connections of a flow
line. In-line process control equipment may include such things as valves, pumps,
flow meters, temperature controllers, pressure controllers and the like. In addition,
ends of pipe sections are provided with flanges so that the sections may be connected,
end-to-end, to form the flow line. It is known to provide gasket devices at the interfaces
of the joined sections to prevent leakage of the fluid at the joint.
[0003] Regardless of the nature of the joint, that is, whether it is between the joined
sections of pipe or whether the joint is used to connect in-line process control equipment,
it is desirable for a gasket device and seal system to be selected based on various
factors that are associated with a particular joint and the particular media that
is conveyed through the joint. These factors include the corrosive nature of the media
flowing through the pipe line as well as the physical characteristics of that flowing
media. Such physical characteristics include the pressure, temperature and velocity
of the media. Additionally, in many cases it is also necessary not only to provide
a reliable seal for the joint but also electrically isolate one side of the joint
from the other. For example, a well known method of corrosion resistance for pipelines
is cathodic protection. This method of corrosion protection requires sealing joints
that provide electrical isolation. Another example is when two sides of the joint
are of dissimilar metals. In this case the electrical potential difference between
the two metals can create a galvanic corrosion cell if the two sides are not electrically
isolated. Finally, it is also desirable for a sealing joint to provide an effective
seal during the event of a fire. Fires pose a very serious threat to the safety of
the pipeline workers and become even more dangerous if the sealing elements between
joints are not capable of containing the media during a fire.
[0004] Therefore, flow line sealing systems face numerous challenges. For example, many
materials which resist corrosive gases are not suitable for high pressure applications
since the materials deform. Materials which are less prone to deformation, such as
a graphite filled spiral wound metal seal, conduct electricity. Many materials that
are used to create seal systems may melt at high temperatures, such as those that
would result in a fire, so that the seal between flanges is compromised. This is an
extremely dangerous situation since compromise of the seal system allows the media,
such as a petroleum or gas product, to rapidly leak from the flow line which can increase
the available combustion products for such a fire. Therefore, a sealing system that
can contain high pressures, electrically isolate and provide safety during a fire
would be a significant improvement in the field of effective flow line sealing.
SUMMARY
[0005] The present disclosure recognizes that a sealing system that can contain high pressures,
electrically isolate and provide safety during a fire would be a significant improvement
in the field of effective flow line sealing. Embodiments disclosed herein provide
sealing systems for high pressure applications that provide electrical isolation between
joined elements as well as enhanced resistance to leakage of media during a fire.
High pressure sealing is accomplished using a metallic core to which an electrically
isolating material is bonded on either or both sides. Sealing is achieved through
a dielectric sealing element, such as a springloaded polytetrafluoroethylene (PTFE)
ring. Flanges of the joint may be bolted together with the seal interposed therebetween,
and the flanges bolted together. In the event of a fire, heat may be generated that
is at a high enough temperature to bum away the isolating material and PTFE ring.
Systems of various embodiments provide a metal core backup seal and a compression
limiter, which, respectively, prevent the media from leaking from the joint.
[0006] One aspect of the present disclosure provides an isolation device for use between
joined pieces in a flow line that is operative for fluid passage therethrough without
leakage. The isolation device of this aspect comprises, for example, a flat metal
plate, such as a flat annular metal plate, having opposing side surfaces and an opening
formed in the metal plate to allow passage of fluid therethrough. In addition, a sheet
of dielectric material is disposed on at least one side surface of the metal plate.
Further, an inner groove and an outer groove are formed on the side surface or surfaces
on which the sheet of dielectric material is disposed, which penetrate through the
dielectric material and into the metal plate and which extend completely around the
opening formed in the metal plate. A primary seal element is disposed in the inner
groove, and a secondary seal element is disposed in the outer groove and there is
a compression limiter acting on this seal in some manner, for example, it could be
disposed in the outer groove or it could be the gasket retainer itself.
[0007] The isolation gasket of the invention is defined in claim 1.
[0008] Other aspects of the present disclosure provide an electrical isolation system between
joined flange pieces, each of which has an inner and an outer face, in a flow line
that is operative for fluid passage therethrough without leakage which utilizing,
for example, a flat metal gasket with an opening formed therein to allow fluid passage
therethrough, which flat metal gasket has opposing side surfaces on which are laminated
sheets of dielectric material, each of which side surfaces has portions defining inner
and outer grooves that penetrate through the layer of dielectric material and into
the metal plate and extends completely around the opening, the inner groove having
a primary seal element disposed therein and the outer groove having a secondary seal
element and a compression limiter acting on said secondary seal.
[0009] In further aspects, the present disclosure provides use of gaskets in combination,
for example, with at least one isolating sleeve receivable in an aligned bore formed
in each of the joined flange pieces, which sleeve has a length that is substantially
equal to a distance between the outer faces of the joined flange pieces with the gasket
interposed therebetween. The isolating sleeve can be made, for example, of glass reinforced
polymer material, epoxy material, phenolic material, or meta-aramid material. Further,
such other embodiments include, for example, at least one elongate metal fastener
with opposing ends, such as a headed metal bolt with threads for receiving a nut,
which fastener is receivable in the isolating sleeve for connecting the joined flange
pieces to one another with the flat metal gasket interposed therebetween.
[0010] Such aspects further comprise, for example, at least one washer made wholly or partly
of materials having electrical isolation properties, such as a sheet of dielectric
material laminated to one side of an annular washer substrate or a metal washer coated
with a dielectric material, which washer is receivable on the elongated metal fastener
with the electrical isolation material abutting one of the flange piece outer faces.
[0011] Still further aspects of the present disclosure provide an electrical isolation device
that comprises a flat metal plate having opposing side surfaces and an opening formed
therein to allow fluid passage therethrough, a layer of dielectric material disposed
on one or both of the opposing side surfaces, at least an inner groove and an outer
groove formed on the side surface or surfaces on which the sheet of dielectric material
is disposed which penetrates through the dielectric material and into the metal plate
and which extends completely around the opening formed in the metal plate. An annular
primary seal element is disposed in the inner groove, and an annular secondary seal
and a compression limiter acting on said secondary seal is disposed in the outer groove.
[0012] These and other advantages and novel features of the disclosure will be set forth
in part in the description which follows, which discloses various embodiments, including
the currently preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
FIG. 1 is a side view in elevation and partial cross-section showing the isolation
gasket and sealing system according to a first exemplary embodiment of the present
disclosure;
FIG. 2 is an enlarged side view in partial cross-section showing a representative
nut and bolt set used with various isolating components for electrically isolating
a flange joint for various exemplary embodiments;
FIG. 3 is a perspective view of an isolation gasket according to an exemplary embodiment;
FIG. 4 is an exploded cross-sectional view of the isolation gasket of FIG. 3 for an
exemplary embodiment;
FIG. 5 is an enlarged cross-sectional view of an inner seal groove of the isolation
gasket of various exemplary embodiments;
FIG. 6 is an enlarged cross-sectional view of an outer seal groove of the isolation
gasket of various exemplary embodiments;
FIG. 7 is a cross-sectional view of a portion of an isolation gasket according to
another exemplary embodiment;
FIG. 8(a)-8(d) are cross-sectional views diagramming various groove cross-sections
that may be used with the isolation gaskets of various different embodiments; and
FIG. 9 is a cross-sectional view partially broken away of an isolation gasket not
in accordance with the present invention.
DETAILED DESCRIPTION
[0014] For a more complete understanding of this invention, reference is now made to the
following detailed description of several embodiments as illustrated in the drawing
figures, in which like numbers represent the same or similar elements. Various embodiments
are described herein, with specific examples provided in many instances to serve to
illustrate and discuss various concepts included in the present disclosure. The specific
embodiments and examples provided are not necessarily to be construed as preferred
or advantageous over other embodiments and/or examples.
[0015] The present invention is generally directed to an isolation gasket adapted to be
used between two flanges in a flow line application. Such flanges may be the flange
connection between two sections of pipeline which are connected in end-to-end relation.
Alternatively, such flanges may be those used to connect monitoring equipment to the
flow line. Accordingly, such a flange connection will be introduced in reference to
the end-to-end connection of a pair of pipeline sections, but it should be clearly
understood that the present invention is not limited to such applications. Thus, for
example, as is illustrated in FIG. 1, an isolation gasket 10 is located in a flange
connection 12 between two pipe sections 14 in a flow line application. Each of the
pipe sections 14 includes flanges 16 which may be placed in confronting relationship
with gasket 10 therebetween. Flanges 16 are provided with bores 20 which align with
one another so that flanges 16 may be connected by nut and bolt sets 18, as is known
in the art.
[0016] With continued reference to FIG. 1, and with reference to FIG. 2, it may be seen
that electrical isolation between flanges 16 is accomplished by a plurality of different
components associated with each aligned pair of bores 20. Here, a pair of aligned
bores 20 is provided with a sleeve 22 constructed, for example, of a glass reinforced
polymer although other materials, such as epoxy, phenolic and nomex materials may
be suitably employed. Sleeve 22 is dimensioned to have a length that is about the
same as the distance between outer surfaces 24 of flanges 16 with gasket 10 interposed
therebetween. Once sleeve 22 has been inserted into a pair of aligned bores 20, isolating
washers 26 are placed on either side of bores 20 on outer surfaces 24 of flanges 16.
In this embodiment, optional metal washers 28 are then positioned against washer 26
and bolt 18 is passed through the washers and sleeve 22 after which it is secured
by nuts 32. This assembly is undertaken for each of the aligned bores 20 after which
nuts 32 may be tightened to compress gasket 10 at a desired pressure.
[0017] Various embodiments described herein contemplate an isolation gasket 10, isolating
washers 26, and sleeves 22 to provide electrical isolation of separate pipe sections
14. Isolating washers 26, as illustrated in FIGS. 1-2, is positioned against outer
surfaces 24 of flanges 16 and, in combination with sleeve 22, provide electrical isolation
between the nut and bolt sets 18 and the flanges 16. The isolating washers 26 may
be metal core washers that are coated with a dielectric material.
[0018] Illustrated in Figs. 3-6, the construction of isolation gasket 10 is described, for
an exemplary embodiment. In this embodiment, isolation gasket 10 includes the gasket
body 38 formed by a flat annular metal plate 40 having an opening 44 therethrough
to allow fluid passage in a flow line application. In one embodiment, the metal plate
40 is formed from 11 gauge stainless steel. Dielectric linings 42 are laminated on
each outer surface of metal plate 40. As illustrated in FIG. 4, a pair of grooves
46 and 48, in this embodiment, are formed on a surface of gasket body 38 with each
of these grooves penetrating through the dielectric linings 42 and into metal plate
40. Groove 48, as illustrated, has a larger diameter than groove 46 so that grooves
46 and 48 are radially offset from one another relative to opening 44. Groove 46 may
be referred to as inner groove 46, and groove 48 may be referred to as outer groove
48. In the embodiment illustrated in FIGS. 4-6, the gasket body 38 has various dimensions
illustrated. As will be understood, these dimensions are illustrative of but one embodiment,
and are provided for purposes of illustration and discussion only. One skilled in
the art will readily recognize that numerous variations may exist for various different
applications and different sizes of flow lines. In this embodiment a 6 inch (15.24
cm) gasket has an opening 44 with a diameter A of 6.000 inches (15.24 cm), an inner
groove 46 diameter B of 6.565 inches (16.68 cm), an outer groove 48 diameter C of
7.838 inches (19.91 cm), and a total diameter D of 9.813 inches (24.93 cm). The total
thickness E of gasket body 38 is 0.308 inches (7.82 mm), which comprises a core thickness
of 0.120 inches (3.05 mm), and a dielectric coating thickness of 0.093 inches (2.36
mm) on each surface. Inner groove 46, illustrated in the detail view of FIG. 5, has
a width F of 0.150 inches (3.81 mm), and a depth G of 0.111 inches (2.82 mm). In this
embodiment, the radially outward side of groove 46 is beveled at an angle of 75 degrees.
Such a beveled surface provides enhanced retention of a seal that is disposed in the
inner groove 46, and as will be discussed in more detail below. The outer groove 48
of this embodiment is illustrated in the detail view of FIG. 6, and has a width H
of .111 inches - 0.252 inches (2.82 mm - 6.40 mm), and a depth I of 0.093 - 0.123
inches (2.36 - 3.12 mm). As will be understood, the dimensions of the embodiment of
Figs. 3 - 6 are exemplary, and other suitable dimensions may be used in various different
applications as will be readily apparent to one skilled in the art.
[0019] As illustrated in FIG. 7, suitable seals 50 and 52 are sized and adapted to be nested
in respective grooves 46 and 48. Seal 50 is disposed in the inner groove 46, and may
be referred to as primary seal 50, because in this embodiment seal 50 provides the
primary sealing for the gasket when installed in a joint. Primary seal 50, in an embodiment,
is a lip seal comprised of a PTFE material having a spring 51 located therein to provide
structural support to the seal 50. The primary seal 50, as illustrated, is a lip seal
that prevents media from passing and is fitted to be seated into groove 46. Groove
46 has a half-dovetail configuration such that, when media applies pressure to seal
50, the seal 50 is pressured against the inside surface of the half-dovetail groove
46 and thus forced into the groove 46. The seal 50, in this embodiment, includes a
beveled edge 53 that helps seat seal 50 in groove 46. Seal 52 is disposed in the outer
groove 48, and may be referred to as a backup or secondary seal 52, because in this
embodiment seal 52 is not exposed to media unless there is a failure in the primary
seal 50. The secondary seal 52, in this embodiment, is comprised of a metal seal having
an E-shape, also referred to as an E-ring seal. The secondary seal 52, in various
embodiments, has a coating of PTFE thereon to provide electrical isolation. Such a
PTFE coating may be, for example, three to five mils (0.076 - 0.127 mm) on an E-ring
made of .0095 inch (2.41 mm) thick Inconel material. A compression limiter 54 could
also be disposed in the outer groove 48. The compression limiter 54, as illustrated
in the embodiment of Fig. 7, may be located in the outer groove 48 adjacent to the
secondary seal 52. A compression limiter may also be integrated such that it is the
gasket retainer itself. In an exemplary embodiment, the compression limiter 54 is
formed of carbon steel and is coated with a dielectric material such as ECTFE (Ethylene-ChloroTriFluoro-Ethylene).
The compression limiter 54 has a thickness that corresponds with the depth of outer
groove 48.
[0020] In normal operation, a gasket body 38 is installed in a flow line joint, with primary
seal 50 containing the media within the joint. In the event of a failure of the primary
seal 50, secondary seal 52 contains the media within the joint. As discussed above,
a common application for such gaskets is in high pressure hydrocarbon pipelines, such
as oil and gas pipelines. Also as discussed above, a significant concern for such
pipelines is fire, and it is desirable to have a gasket that will maintain a seal
even in the event of a significant fire. The gasket of the embodiments of Figs. 3-7
provides enhanced performance in the event of a fire. In such an event, high temperatures
of the fire may melt or bum away the primary seal 50 as well as the dielectric coating
42 on the gasket body 38. Thus the primary seal 50 fails, but secondary seal 52, being
formed of a metal, maintains the media within the joint. As mentioned, the loss of
the dielectric coating 42 also may occur, which results in the gasket thickness E
being reduced. Compression limiter 54 acts to maintain a virtual gasket thickness
E in such an event, which acts to help maintain the appropriate loads on the bolts
18 that hold the flanges 16 of the joint together and not allow the secondary seal
to be over compressed due to the gasket thickness E being reduced. In the absence
of a compression limiter 50, when dielectric coating 42 is reduced, the bolt load
on bolts 18 is also reduced, thereby resulting in a loose joint which may result in
media leaking from the joint. Thus in such a situation, a compression limiter, such
as compression limiter 50, acts to help maintain bolt load and not allow the seal
to be over compressed. In the event of a fire and the loss of the isolating dielectric
coating 42, the sides of the joint are no longer electrically isolated, however, such
an event will require repair of the flow line and replacement of the gasket in any
event.
[0021] With reference now to Figs. 8(a)-8(d), it should be appreciated that various configurations
of grooves, such as grooves 46 and 48 may be employed with the present invention.
For example, in Fig. 8(a) groove 80 is a rectangular cross-section groove formed through
dielectric material 42 and into metal core 40. FIG. 8(b) provides a groove 82 that
is a trapezoidal dovetail configuration. Groove 82 is again cut through dielectric
layer 42 and into metal core 40. In FIG. 8(c), groove 84 has the cross-section of
a parallelogram and is again formed through isolating layer 42 and into metal core
40. Finally, FIG. 8(d) illustrates a trapezoidal groove 86 having one side thereof
oriented at a right angle to the base. Groove 86 is cut through dielectric layer 42
and into metal core 40. One skilled in the art will readily recognize that such groove
configurations are exemplary only, and that othes groove configurations may be used.
[0022] With reference now to Fig. 9, another gasket not in accordance with the present invention
is described. Fig. 9 is a cross-sectional illustration of one half of a gasket 100.
Illustrated in Fig. 9, is a gasket 100 comprising a metal core 104 and dielectric
layers 108 on each side of the metal core. Inner groove 112 and outer groove 116 are
formed in the gasket 100, each of which extending through the dielectric layer 108
and into metal core 104. In some embodiments, inner groove 112 may not penetrate entirely
through dielectric layer 108, and outer groove 116 may penetrate through the dielectric
layer 108 and into the metal core 104. As illustrated in FIG. 9, suitable seals 120
and 124 are sized and adapted to be nested in respective grooves 112 and 116. Seal
120 is disposed in the inner groove 112, and may be referred to as primary seal because
in this embodiment seal 120 provides the primary sealing for the gasket when installed
in a joint. Primary seal 120, in an embodiment, is comprised of a PTFE material having
a spring located therein to provide structural support to the seal 120. The primary
seal 120 may, in operation, be a lip seal that prevents media from passing. Seal 124
is disposed in the outer groove 116, and may be referred to as a backup or secondary
seal 124, because in this embodiment seal 124 is not exposed to media unless there
is a failure in the primary seal 120. The secondary seal 124, in this embodiment,
is comprised of a metal seal having an E-shape, also referred to as an E-ring seal.
The secondary seal 124, in various embodiments, has a dielectric coating thereon to
provide electrical isolation. Such a coating may be, for example, a PTFE coating that
is three to five mils (0.076 - 0.127 mm) in thickness on an E-ring made of metal.
The gasket 100 of this embodiment has varying depths of the inner groove 112 and outer
groove 116, thereby providing a compression limiter for the secondary seal 124. In
such a manner, if dielectric layers 108 are reduced, the metal core 104 will remain,
with secondary seal 124 disposed in the outer groove 116. The depth of the outer groove
116 into the metal core 104 is such that the secondary seal 124 is less likely to
be over compressed, and thus will continue to provide a seal.
[0023] In another embodiment, the gasket may include a single groove rather than dual grooves.
In such an embodiment, the gasket, similarly as described above, may include a metal
core and dielectric layers on each side of the metal core. The single groove may be
formed in the gasket, extending through the dielectric layer and into metal core.
A single seal is adapted to be nested in the single groove. In such an embodiment,
the single seal is comprised of a metal seal having an E-shape, also referred to as
an E-ring seal, although other configurations may be used. The single seal of such
an embodiment may have a dielectric coating thereon to provide electrical isolation.
Such a coating may be, for example, a PTFE coating that is three to five mils (0.076
- 0.127 mm) in thickness on an E-ring made of metal. The gasket of such an embodiment
may also provide a compression limiter for the single seal. Such a compression limiter
may include any compression limiter such as described above, such as carbon steel
coated with a dielectric material, or the configuration of the depth of the groove
relative to the metal core such that the single seal 124 is less likely to be over
compressed in the event that the dielectric layer is reduced.
[0024] As will be appreciated by those skilled in the art, industries such as the oil and
gas industry utilize many, many miles of connected metal pipelines that are subjected,
for example, to a natural flow of current through the pipeline and across the metal-to-metal
flange connections in the pipeline which causes the flange connections to corrode
and build up corrosion similar to battery terminals. The isolation gasket for embodiments
of the invention interrupts that current flow through a pipeline and prevents the
flanges from corroding and building up corrosion in the way in which they would with
a metal-to-metal seal.
[0025] It is to be understood that embodiments of the invention cover a wide range of applications,
including without limitation, not only isolation but also potential fire safety, such
as fire sealing applications. In that regard, combinations including washers for embodiments
of the invention are significant aspects of the invention because, for example, if
the washer material deforms or begins to flow because of heat, bolt load will be lost.
If the bolt load is lost, there is no longer any compression in the joint between
the two flanges in the flow line, which means the gasket no longer seals the joint.
Further to this point, having a dielectric coating on the face of the gasket body
that eventually loses thickness due to fire can result in over compression of metal
formed seals. Thus a compression limiter of some type is provided to help both bolt
load loss and seal over compression.
[0026] It is to be further understood that a method of making the gasket material for embodiments
of the invention involves bonding the dielectric lining material to both sides of
the metal substrate in large sheets to assure uniformity of the lamination. According
to such a method, a water jet is thereafter utilized to cut appropriately dimensioned
LD and O.D. circles for gaskets out of the large sheets, and the grooves are formed
on opposite sides of the cut-out circular gasket material, for example, with the circular
gasket material mounted on a lathe. The resulting isolation gasket for embodiments
of the invention has the stability and/or rigidity of a metal gasket with a stainless
steel core having excellent corrosion resistance properties, while the glass reinforced
epoxy laminated to the opposing surfaces of the gasket provides excellent isolating
properties.
[0027] As likewise previously noted, another important aspect of embodiments of the invention
is the seating of a suitable type of seal in the grooves of the gasket body. Representative
examples of seal options include spring energized PTFE seals, as well as other types
of O-ring or soft material as a back-up seal, or metal seals coated, for example,
with a softer isolating material, such as PTFE. As similarly previously noted, a further
important aspect of embodiments of the invention is the shape of the grooves formed
in the gasket body. A factor in selecting one or more of the groove shapes previously
described is the particular type of seal that is intended to be used. As internal
pressure acts on the seal, the shape of the groove provides support for the seal and
helps prevent the seal from blowing out. Thus, as will be readily recognized by one
of skill in the art, a groove with a particular cross section may provide better support
and enable better sealing characteristics for a particular type of seal element than
a groove with a different cross section.
[0028] The previous description of the disclosed embodiments is provided to enable a person
skilled in the art to make or use the present invention. Various modifications to
these embodiments will be readily apparent to those skilled in the art, and the generic
principles defined herein may be applied to other embodiments without departing from
the scope of the invention.
1. An isolation gasket (10) for use between joined pieces in a flow line that is operative
for fluid passage therethrough, comprising:
an metal plate (40) having opposing side surfaces and an opening formed therein to
allow fluid passage therethrough;
a primary seal (50) coupled to the isolation gasket (10);
a layer of dielectric material (42) disposed on at least one of said opposing side
surfaces;
a groove (48), having a depth, formed on at least one of said opposing side surfaces
which penetrates through said layer of dielectric material and into said metal plate
and which extends completely around said opening;
a secondary seal (52) comprising an annular body seal element formed at least in part
of metal disposed in said groove; and
a compression limiter (54), having a thickness that corresponds with the depth, acting
on the secondary seal;
the compression limiter acting to maintain a thickness of the isolation gasket in
the event of high temperatures causing the loss of dielectric material and the primary
seal to fail and preventing the secondary seal from being over compressed.
2. The isolation gasket of claim 1, wherein said metal plate further comprises a flat
annular metal plate.
3. The isolation gasket of claim 1, further comprising a layer of dielectric material
disposed on each of said opposing side surfaces.
4. The isolation gasket of claim 3, wherein said layer of dielectric material is laminated
to each of said opposing side surfaces.
5. The isolation gasket of claim 3, further comprising a groove formed on each of said
opposing side surfaces, each of which penetrates through said layer of dielectric
material and into said metal plate, and each of which extends completely around said
opening.
6. The isolation gasket of claim 1, wherein groove has a cross section that is one of
a rectangular shape, an isosceles trapezoid shape, a trapezoid shape, or a parallelogram
shape.
7. The isolation gasket of claim 1, wherein said secondary seal has a coating of dielectric
material.
8. The isolation gasket of claim 1, wherein said secondary seal comprises an E-ring seal
element.
9. The isolation gasket of claim 1, wherein said compression limiter comprises the flat
metal plate and dielectric material, the depth of said groove selected such that said
secondary seal is not over compressed when said layer of dielectric material is reduced.
10. The isolation gasket of claim 1, wherein said compression limiter is an annular metal
ring disposed in said groove adjacent to said secondary seal.
11. The isolation gasket of claim 10, wherein said compression limiter is coated with
dielectric material.
1. Isolierdichtung (10) zur Verwendung zwischen verbundenen Teilen in einer Strömungslinie,
die für einen Fluiddurchgang hier hindurch zuständig ist, aufweisend:
eine Metallplatte (40) mit einander gegenüberliegenden Seitenflächen und einer Öffnung,
die darin gebildet ist, um einen Fluiddurchgang hier hindurch zu ermöglichen;
eine erste Dichtung (50), die an die Isolierdichtung (10) gekoppelt ist;
eine Schicht eines dielektrischen Materials (42), das auf mindestens einer der einander
gegenüberliegenden Seitenflächen angeordnet ist;
eine Nut (48) mit einer Tiefe, die auf zumindest einer der einander gegenüberliegenden
Seitenflächen gebildet ist, die durch besagte Schicht eines dielektrischen Materials
hindurchgeht und ferner in besagte Metallplatte reicht, und die sich vollständig um
besagte Öffnung erstreckt;
eine zweite Dichtung (42), die ein ringförmiges Körper-Dichtelement aufweist, das
zumindest teilweise aus Metall gefertigt und in besagter Nut angeordnet ist; und
einen Druckbegrenzer (54) mit einer Dicke, die der Tiefe entspricht und auf die zweite
Dichtung wirkend;
wobei der Druckbegrenzer ein Erhalten einer Dicke der Isolierdichtung in dem Fall
von hohen Temperaturen wirkt, was zum Verlust an dielektrischen Material führt und
zu einer Fehlfunktion der ersten Dichtung und die zweite Dichtung vor einer Überkompression
bewahrt.
2. Isolierdichtung nach Anspruch 1, wobei die Metallplatte ferner eine flache ringförmige
Metallplatte aufweist.
3. Isolierdichtung nach Anspruch 1, ferner aufweisend eine Schicht aus dielektrischem
Material, angeordnet auf einer jeweiligen der einander gegenüberliegenden Seitenflächen.
4. Isolierdichtung nach Anspruch 3, wobei die Schicht aus dielektrischem Material auf
einer jeweiligen der einander gegenüberliegenden Seitenflächen laminiert ist.
5. Isolierdichtung nach Anspruch 3, ferner aufweisend eine Nut, die auf einer jeweiligen
der einander gegenüberliegenden Seitenflächen ausgebildet ist, wobei jede dieser Nuten
durch besagte Schicht aus dielektrischem Material hindurchgeht und in besagte Metallplatte
ragt, und wobei jede dieser Nuten sich vollständig um besagte Öffnung erstreckt.
6. Isolierdichtung nach Anspruch 1, wobei die Nut einen Querschnitt hat, der einer rechteckförmigen
Gestalt, einer gleichschenkligen Trapezgestalt, einer Trapezgestalt oder einer Parallelogramm-Gestalt
entspricht.
7. Isolierdichtung nach Anspruch 1, wobei die zweite Dichtung eine Ummantelung aus dielektrischem
Material hat.
8. Isolierdichtung nach Anspruch 1, wobei die zweite Dichtung ein E-Ring-Dichtelement
aufweist.
9. Isolierdichtung nach Anspruch 1, wobei der Druckbegrenzer die flache Metallplatte
und dielektrisches Material aufweist, wobei die Dichte der besagten Nut so ausgewählt
ist, dass die zweite Dichtung nicht überkomprimiert wird, wenn die Schicht aus dielektrischem
Material reduziert wird.
10. Isolierdichtung nach Anspruch 1, wobei der Druckbegrenzer ein ringförmiger Metallring
ist, der in besagter Nut angrenzend zur zweiten Dichtung angeordnet ist.
11. Isolierdichtung nach Anspruch 10, wobei der Druckbegrenzer mit dielektrischem Material
ummantelt ist.
1. Joint d'isolation (10) destiné à être utilisé entre des pièces jointives dans une
canalisation d'écoulement qui est opérationnelle pour laisser passer un fluide à travers
celle-ci, comprenant :
une plaque métallique (40) qui présente des surfaces latérales opposées et une ouverture
formée à l'intérieur de façon à permettre le passage d'un fluide à travers celle-ci
;
un joint primaire (50) accouplé au joint d'isolation (10) ;
une couche de matériau diélectrique (42) disposée sur l'une au moins desdites surfaces
latérales opposées ;
une gorge (48), qui présente une profondeur, formée sur l'une au moins desdites surfaces
latérales opposées, qui pénètre à travers ladite couche de matériau diélectrique et
dans ladite plaque métallique, et qui s'étend en totalité autour de ladite ouverture
;
un joint secondaire (52) qui comprend un élément de joint de corps annulaire formé
dans une partie de métal au moins, disposé dans ladite gorge ; et
un dispositif de limitation de compression (54), qui présente une épaisseur qui correspond
à la profondeur, et qui agit sur le joint secondaire ;
le dispositif de limitation de compression agissant de façon à maintenir l'épaisseur
du joint d'isolation dans un cas où des températures élevées provoqueraient une perte
de matériau diélectrique et une défaillance du joint primaire, et empêchant le joint
secondaire de subir une surcompression.
2. Joint d'isolation selon la revendication 1, dans lequel ladite plaque métallique comprend
en outre une plaque métallique annulaire plate.
3. Joint d'isolation selon la revendication 1, comprenant en outre une couche de matériau
diélectrique disposée sur chacune desdites surfaces latérales opposées.
4. Joint d'isolation selon la revendication 3, dans lequel ladite couche de matériau
diélectrique est stratifiée sur chacune desdites surfaces latérales opposées.
5. Joint d'isolation selon la revendication 3, comprenant en outre une gorge formée sur
chacune desdites surfaces latérales opposées, qui pénètre à travers ladite couche
de matériau diélectrique et dans ladite plaque métallique, et qui s'étend en totalité
autour de ladite ouverture.
6. Joint d'isolation selon la revendication 1, dans lequel la gorge présente une section
transversale dont la forme est celle d'un rectangle, d'un trapèze isocèle, d'un trapèze,
ou d'un parallélogramme.
7. Joint d'isolation selon la revendication 1, dans lequel ledit joint secondaire présente
un revêtement de matériau diélectrique.
8. Joint d'isolation selon la revendication 1, dans lequel ledit joint secondaire comprend
un anneau truarc E en tant qu'élément de joint.
9. Joint d'isolation selon la revendication 1, dans lequel ledit dispositif de limitation
de compression comprend la plaque métallique plate et le matériau diélectrique, la
profondeur de ladite gorge est sélectionnée de telle sorte que ledit joint secondaire
ne soit pas surcomprimé lorsque ladite couche de matériau diélectrique est réduite.
10. Joint d'isolation selon la revendication 1, dans lequel ledit dispositif de limitation
de compression est un anneau métallique annulaire disposé dans ladite gorge, adjacent
audit joint secondaire.
11. Joint d'isolation selon la revendication 10, dans lequel ledit dispositif de limitation
de compression est revêtu avec le matériau diélectrique.